System and method for piecewise streaming of video using a dedicated overlay network

ABSTRACT

The main challenge in providing video on demand service is to meet the quality of service requirements under the conditions when both server and network are loaded. Disclosed is a system and method for meeting this challenge by using a streaming overlay network with edge and core nodes, by the determination of best possible path for bulk copying of a video data based on location information of the nodes thereby distributing load across the network, by the simultaneous frame streaming and bulk copying of a video data, by the caching of a video data in the overlay network, and by the streaming of the video data to a client from an edge node that is close to the client.

FIELD OF THE INVENTION

[0001] The present invention relates to video streaming in general, and more particularly, video streaming under network and server loaded conditions. Still more particularly, the present invention relates to a system and method for piecewise streaming of video using a dedicated overlay network.

BACKGROUND OF THE INVENTION

[0002] Video on demand as a service needs adequate infrastructure (network and servers) to meet Quality of Service (QoS) requirements. Relevant QoS parameters are time to start of the video and sustainable frame rate. Both these parameters are affected when a server that is to stream a video to a client and a network through which the server and the client are connected are loaded. However, the absolute loading of the network is relatively infrequent and it is useful to deploy approaches that exploit the network as a whole thereby overcoming the bottleneck due to relative loading situations. Relative loading indicates that the select paths in the network are overloaded while the rest of the paths are not so loaded. The approaches that exploit the network as a whole offers several advantages including being able to meet QoS requirements under trying conditions, being able to provide a best possible interactive environment for interacting with the video servers, and being able to enhance the return on investment on network and server infrastructure.

[0003] A network that supports video streaming can either be a public, general purpose network or a dedicated, special purpose network. Taking into account the cost of providing Video on Demand (VoD) services, it is essential to deploy a suitable mix of public and private networks. The dedicated network is primarily used to address the requirements related to the core activity of the VoD service while the public network is used for meeting the non-core activities of the video-service. A way to effectively meet the core activity of the VoD service is to determine a best possible path for streaming video when the network is loaded. There are several approaches for determining the best possible path and as this path determination is done in real-time, the deployed approach must be quite efficient. Furthermore, the overall approach must be scalable as the resource requirements of a deployed service normally increases with time.

[0004] Caching provides an additional way for effectively utilizing the network infrastructure. Caching of the video data helps in reducing the load on the video server as well as on the network. By using the cache effectively along with the point of presence of nodes of the dedicated network, it is possible to offer the video service in a best possible manner.

DESCRIPTION OF RELATED ART

[0005] U.S. Pat. No. 6,195,680 to Goldszmidt; German Sergio (Dobbs Ferry, N.Y.); Willebeek-LeMair; Marc Hubert (Yorktown Heights, NY); Hon; Kenneth Sau-yee (Mid-Levels, HK) for “Client-based dynamic switching of streaming servers for fault-tolerance and load balancing” (issued on Feb. 27, 2001 and assigned to International Business Machines Corporation (Armonk, N.Y.)) describes a client based system for the fault tolerant delivery of real-time or continuous data streams such as real-time multimedia streams. Multimedia servers are grouped into two or more sets wherein the first set includes one or more primary servers and the second set includes one or more secondary servers. The client receives a stream directly from a selected primary server. On automatic detection of load imbalance and/or failures, the client dynamically switches to a secondary server in order to continue receiving of the real-time multimedia with minimal disruption.

[0006] U.S. Pat. No. 6,275,470 to Ricciulli; Livio (Los Gatos, Calif.) for “On-demand overlay routing for computer-based communication networks” (issued on Aug. 14, 2001 and assigned to Digital Island, Inc. (San Francisco, Calif.)) describes an appropach for dynamically discovering and utilizing an optimized network path through overlay routing for the transmission of data. A determination whether to use default network path or to instead use an alternate data forwarding path through one or more overlay nodes is based on real-time measurement of costs associated with the alternate paths, in response to a user request for transmission of message data to a destination on the network. The system chooses best path among the default forwarding path and the multiple alternate forwarding paths.

[0007] U.S. Pat. No. 6,502,139 to Birk; Yitzhak (Hod Hasharon, Ill.); Mondri; Ron (Haifa, Ill.) for “System for optimizing video on demand transmission by partitioning video program into multiple segments, decreasing transmission rate for successive segments and repeatedly, simultaneously transmission” (issued on Dec. 31, 2002 and assigned to Technion Research and Development Foundation Ltd. (Haifa, Ill.)) describes a system and method for near video on demand transmission of a program from a server to multiple clients. The program is partitioned into multiple segments and each segment is transmitted at different transmission rates. The transmission of segments is scheduled in a manner that minimizes the aggregate transmission bandwidth subject to constraints related to client parameters such as client storage capacity and client recording rates.

[0008] Xu Lin and Ivan Stojmenovic in “GPS based distributed routing algorithms for wireless networks” (appeared in 2000, unpublished manuscript) describe a location based geographic distance routing algorithm. When a source node wants send a message to a destination node, it forwards the message to an intermediate neighboring node that is closest to the destination node among all neighbors of the source node and this is repeated until eventually the destination node is reached.

[0009] Young-Bae Ko and Nitin H. Vaidya in “Location-Aided Routing (LAR) in Mobile Ad Hoc Networks” (appeared on October, 1998 in Proceedings of the Fourth Annual ACM/IEEE International Conference on Mobile Computing and Networking) describe a fully distributed routing protocol in a wireless ad hoc network based on the direction of destination. This paper suggests an approach to utilize location information to limit the search for a new route to a smaller request zone of the ad hoc network, thereby significantly reducing the number of routing messages.

[0010] The known systems do not address the issue of effective utilization of an overlay network to stream videos to the demanding clients under the conditions when both network and server are loaded. The disclosed invention provides with a system in which an overlay network infrastructure is efficiently utilized by using a location based routing approach and utilizes the video server infrastructure efficiently by (a) streaming from the edge nodes of the overlay network; and (b) transparently switching from one edge node to another.

SUMMARY OF THE INVENTION

[0011] Meeting the QoS requirements of a video service under the conditions when both network and server are loaded is a difficult task. The present invention provides a system and method for effectively utilizing the server resources by streaming the video from the edge nodes of a dedicated streaming overlay network and the network infrastructure is utilized effectively by using the location based bandwidth allocation and management, and piecewise streaming, thereby addressing the issues related to QoS under loaded conditions.

[0012] One aspect of the invention is to provide a method for using a hierarchical streaming overlay network to support scalability to accommodate a large number of video servers and video clients.

[0013] Another aspect of the invention is to provide a method for a video server to interact with a pre-defined edge node of a streaming overlay network on receiving a request for a video from a client and to transfer the video file to the edge node on demand.

[0014] Another aspect of the invention is to provide a method for a video client to receive a requested video from multiple servers during the course of video streaming.

[0015] Yet another aspect of the invention is to provide a method for an edge node to bulk copy a video file to another edge node by utilizing one or more intermediate core nodes in such a way that the available bandwidth is maximally utilized and the file gets copied in a shortest possible time.

[0016] Yet another aspect of the invention is to provide a method for a streaming overlay network to stream a video file to a video client in such a way that the streaming gets started as quickly as possible.

[0017] Another aspect of the invention is provide a method for routing table management in an edge node of a streaming overlay network in such a way that the routing table at any point in time denotes an accurate description of the available bandwidth between any pair of neighboring nodes in a streaming overlay network.

[0018] Yet another aspect of the invention is to provide a method for maintaining a routing table in an edge node of a streaming overlay network in such a way that the routing table in edge nodes of the streaming overlay network are in sync with each other.

[0019] Another aspect of the invention is to provide a method for location based routing to determine a best possible path within a streaming overlay network so that the load gets distributed across the streaming overlay network.

[0020] Another aspect of the invention is to provide a method for cache management to store video data across a streaming overlay network so that video streaming of a video data in response to a request from a client gets started as quickly as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 describes an overall system architecture of PWVS system.

[0022]FIG. 2 describes a network architecture related to PWVS system.

[0023]FIG. 2A describes a SON hierarchical network architecture.

[0024]FIG. 3 depicts a typical sequence flow in PWVS system.

[0025]FIG. 4 depicts the schema of various database tables related to PWVS system.

[0026]FIG. 5 depicts the steps involved in receiving and displaying video data by a video client.

[0027]FIG. 5A describes the steps involved in servicing of a video demand from a client.

[0028]FIG. 6 depicts the steps involved in bulk copying.

[0029]FIG. 7 describes the steps involved in frame streaming.

[0030]FIG. 8 describes the various factors involved in routing table management.

[0031]FIG. 9 describes the steps involved in bandwidth management.

[0032]FIG. 10 describes the steps involved in token management.

[0033]FIG. 11 describes the steps involved in determining a route from a source node to a target edge node.

[0034]FIG. 12 describes the various factors involved in video file cache management.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035]FIG. 1 describes an overall system architecture of PWVS system. The main component of the system is the Streaming Overlay Network (SON). The SON is a dedicated network to efficiently meet real-time demands for video. A VoD service needs to address the QoS aspects the service such as time to start streaming and quality of video transmission. Both these QoS aspects are worst affected when the network is loaded and it is a real and big challenge for video service providers to adhere to Service Level Agreements (SLAs) under these trying conditions. There are two bottleneck points in the infrastructure used in streaming: (a) the network that transports video data; and (b) the host (video server) that is the source of the stream. The architecture proposed in FIG. 1 helps in overcoming these bottlenecks and in addressing the challenges head-on. The purpose of SON is to have a point of presence (PoP) as close to the video clients as possible and in the proposed architecture, such PoPs are used effectively during the network congestion and host congestion times to minimize the impact of the same on QoS of video service.

[0036] In order to stream a video from a server to a client, it is necessary to have a sufficient bandwidth (BW) for the entire duration of the video streaming. This calls for demanding bandwidth on network that can ultimately become a bottleneck. It has also been observed that while there is a congestion on some select routes in the network, the overall load on the network doesn't overload the network. The objective is to exploit this bandwidth availability without compromising on QoS. A typical video streaming consists of a sequence of frames to be streamed at an agreed upon frame rate. On account of this factor, not only this requires an end to end bandwidth but also a constant allocation of server resources. SON, a dedicated multi-node network, is positioned in between multiple servers and multiple clients to help reduce the load on both the network and servers. In the proposed architecture, a collection of edge nodes manage the overall bandwidth available within SON by appropriately loading the various core nodes.

[0037] On receiving a client request for a video, the video server interacts with a configured source edge node of the SON. Similarly, the client is configured to receive video data from a target edge node of the SON. The approach is to get the video as quickly as possible to the target edge node so that the chances of network and video server congestion affecting the video transmission is greatly reduced. At the same time, it is important to initiate streaming of the video to the client as early as possible. Both these factors are achieved by the source edge node by (a) streaming the video to the client through an IP network such as Internet or intranet, and (b) initiating the transfer of the video file from the source edge node to the target edge node. While the streaming is in progress, the source edge node identifies a best possible path with the best possible bandwidth to a best possible intermediate core node that is in the direction of the target edge node and transfers the video data in a shortest possible time. The idea is, instead of compromising for a low bandwidth end-to-end path from the source edge node to the target edge node, to determine piecewise maximal (from the point of view of bandwidth) sub-paths and transfer the video file using these maximal sub-paths. This exploits the available bandwidth within SON in a flexible way and at the same time attempts to reduce the overall video file transfer time. Note that this transfer is not affected by the agreed upon frame rate for video streaming.

[0038] Another important aspect of the proposed system is cache management. As more and more video files get transferred to edge nodes, during such transfers, the video files get stored and forwarded by multiple core nodes. All the nodes in SON have adequate storage infrastructure to store and forward video files and hence this storage can be used to effectively to increase the overall throughput. This is achieved by managing the store as a cache and retaining those video files in the storage that are likely to be accessed. When there is a need for accommodating additional video files, those video files in the cache that are least recently accessed are removed from the store to make room for new video files. As a consequence of distributed cache across the nodes of the SON, a client video request is analyzed to determine the best possible core or edge node that can be used to address the client demand. Specifically, if the video being requested is already present in an edge node that is closest to the client, then it is a simple matter to start the video streaming with the least overhead. On the other hand, if the requested video is present in one of the core nodes, then video streaming and video transferring are started from this core node simultaneously instead from a source edge node, thereby enhancing the throughput.

[0039] The edge nodes not only load the core nodes but also maintain the status of various core nodes and their associated links. This is facilitated by the self-monitoring aspect of the core nodes and these nodes communicate health messages at regular intervals to the edge nodes. Also, a core node monitors its neighbors and communicates their status to the edge nodes. In order to ensure that these health messages reach edge nodes, a portion of the network bandwidth is kept aside for this purpose. Using this and additional topological information, each edge node is in a position to arrive at a available bandwidth matrix that indicates the amount of bandwidth available at any point in time between any pair of nodes. Note that this bandwidth is an aggregated bandwidth across multiple links of a node. Whenever piecewise maximal sub-paths are determined to transfer video files, this information is updated onto the available bandwidth matrix and also communicated to the rest of the edge nodes to maintain a consistent BW availability information. Since this is a crucial requirement, this is addressed in the proposed architecture by (a) reserving bandwidth along the paths connecting the edge nodes into a ring topology, and (b) using token based updation of available bandwidth matrix. The first requirement is met by an explicit bandwidth reservation while the second requirement is met by selecting one of the edge nodes to act as a token manager. The rest of the nodes interact with this selected edge node to obtain the token before updating the available bandwidth matrix.

[0040] In order to effectively identify piecewise maximal bandwidth sub-paths that together provide an end-to-end path between source and target edge nodes, it is proposed to use the location information. Specifically, each node has a location attribute that is the physical location of the node. This is used in identifying intermediate core nodes that are in the direction of the target node from the source node, thereby identifying the best possible core nodes.

[0041] An interactive video client (102) interacts with a video server (104) via an IP network such as Internet/intranet (106) to request for a video. This request is communicated to the source edge node (108) by the video server. The main components of an edge node (108 and 112) are: (a) Bulk Copying—to transfer a video file from a source node to a core node with an ultimate objective of reaching a target edge node; (b) Frame Streaming—to stream a video file from a node to a client and if the node is not a target node, then the streaming is till such time the video transfer to the target node is under progress while if it is the target node (112), then the streaming is till the completion of the video; (c) Bulk Caching—storing of a received video file in the local storage of a node for forwarding and streaming purposes; (d) Routing and Bandwidth Management—to maintain the status of the SON along with the bandwidth availability and connectivity information; (e) Cache Management—to manage the local store containing a collection of video files so as to ensure that the store contains the most likely needed video files. The main components of a core node (110) are: (a) Bulk Copying—to forward a video file contained in the local cache to another core node or to an edge node; (b) Frame Streaming—to stream a video file to a client via an edge node and an IP network such as Internet/intranet; (c) Bulk Caching—to store the received video files in the local storage for forwarding and streaming purposes; (d) Routing—to reserve bandwidth and route packets along a path. The network connecting edge nodes and core nodes is the streaming overlay network (114) that is a dedicated network to stream videos to clients in an effective manner.

[0042]FIG. 2 describes a network architecture related to PWVS system. The architecture depicts multiple video clients (202) connected to multiple video servers (204) through an IP network Such as Internet/intranet (206). In a typical video service, this is all could be the infrastructure. However, to overcome the various challenges and bottlenecks due to network and host congestion, a streaming overlay network is introduced as part of the PWVS network architecture (210). SON contains multiple edge nodes (212) and multiple core nodes (214). These edge and core nodes are interconnected yielding a particular network topology. Each video server is connected to an edge node of SON and further, each edge node is connected to the IP network.

[0043]FIG. 2A describes a SON hierarchical network architecture. The suggested hierarchical extension supports scalability and also is a way of containing the complexity of individual SONs. In one of the preferred embodiments, video servers are connected to leaf SONs (220) while intermediate, non-SON nodes (222) are used to interconnect efficiently leaf SONs. Also, the edge nodes of leaf SONs that act as POPs for video clients are connected to an IP network such as Internet/intranet through which clients and servers are interconnected:

[0044]FIG. 3 depicts a typical sequence flow in the PWVS system. 302 describes a sequence related to the processing of a client request for a video when that video is not present in the SON distributed cache. In this case, the video server sends the video file to a source edge node, which in turn sends the video file, via multiple intermediate core nodes, to a target node. This target node is the POP node for the video client and the target node resumes video streaming to the client after the successful completion of transfer of the video file.

[0045]FIG. 4 depicts the schema of various database tables related to PWVS system. 402 describes Video Cache table that contains information to manage cache. There are two variations of cache maintained in a distributed manner in SON: edge cache and core cache. 404 describes Video Streams table providing information related video streaming by edge and core nodes to various clients. The clients are identified by their IP address. 406 describes Node Locations table that contains information related to physical location of various core and edge nodes. Node type explicitly identifies a node as either core or as edge node. 408 describes Connectivity/Available Bandwidth Matrix. This table contains the most recent information related to the bandwidth availability between any two neighboring nodes. 410 describes BW Table that provides a node-wise consolidated information regarding total and available bandwidth.

[0046]FIG. 5 depicts the steps involved receiving and displaying video data by a video client. Interactive video client I sends request to a video server V for a video VF (502). I is configured to receive video from an edge node T of the SON (504). I receives input from VF regarding the edge node S of the SON and opens connection with S (506). On receiving input from S (508), I checks whether source of video is S or T (510). If the source is from S where S is an edge node of the SON related to V, I receives input from S (512) and checks whether input data is a frame data or control data (514). If it is a frame data, the received frame data is buffered (516) and the buffered data is used for displaying (518). The steps 512 through 518 are repeated till control data is received from S. On the other hand, if the control data is received (514) and if the received control data indicates end of data (520), I closes the connection with S (522). Otherwise, a check is made to determine if the data is related to informing a change in source of video (520). If it is so, the change over frame number F is received from S (524). I receives, buffers, and displays frames till frame F−1 is received (526). I closes the connection with S and opens connection with T (528). By default, I is configured to received video data from the edge node T. Frame F onwards is received from the node T. On the other hand, if the input received from S indicates that the source of video is T (510), I closes connection with S and opens connection with T (530) and I receives input from T (532). A check is made to determine whether the received input is frame data (534). If so, the received data is buffered (536) and displayed (538). The steps 532 through 538 are repeated till the completion of streaming of VF. On the other hand, if the received input is control data signaling end (534), I closes the connection with T (540).

[0047]FIG. 5A describes the steps involved in servicing of a video demand from a client. VoD service on a video server V receives a video demand request from a client 1 (552). I is configured to receive video from T and V is configured to interact with S where S and T are edge nodes of the SON (554). On receiving request from I, V sends request to S to determine whether the video VF is already present in the distributed cache of the SON (556). S checks for the availability of VF in the SON cache (558). If VF is not found in the cache, S informs the same to V and V sends VF to S (560). S stores the received video file VF and starts streaming VF to I via Internet/intranet (562). Simultaneously, VF is bulk copied to T that is close to I as quickly as possible (564). As frame streaming to I is under progress from S, based on current frame, S determines frame number F ahead of the current frame and communicates the current frame number, time stamp, and F to T to initiate the streaming to I from F (566). T computes the time at which to start the streaming from frame number F onwards based on the received current frame number, time stamp, frame rate, and F, and starts streaming to I. S stops streaming after streaming up to frame F−1 from S (568). On the other hand, if VF is located in cache of S (570) and processing continues from step 562 onwards. If VF is located in a core node C of the SON (572), S locates VF in cache. C starts frame streaming of VF to I via T that is close to 1 (574). Simultaneously, C bulk copies VF to T (576). As frame streaming to I is under progress from C, based on current frame, C determines frame number F ahead of the current frame and communicates the current frame number, time stamp, and F to T to initiate the streaming to I from F (578). T computes the time at which to start the streaming from frame number F onwards based on the received current fi-ame number, time stamp, frame rate, and F, and starts streaming to I. C stops streaming after streaming up to frame F−1 to I (580). If VF is located in T (582), T starts frame streaming of VF to I (584).

[0048]FIG. 6 depicts the steps involved in bulk copying. Bulk copying refers to activity of transferring the video file being streamed to a client to an edge node (PoP node), on the SON that is as close to the client as possible, as quickly as possible. The objective is to continue streaming of the video file to the client from the PoP node once the transfer is successfully completed. Bulk copying makes best use of the network infrastructure thereby enhancing the return on investment. The described procedure achieves bulk copying of a video file from a node Y to a target edge node T (602). If Y is not an edge node, let S be an edge node based on cache table at node Y indicating that the video file being bulk copies was originally sourced to Y from S, otherwise let S be Y. Let current node be Y. Obtain a best possible path P from the current node to node C (604). The node C can either be an intermediate core node or edge node T. The best path is based on the maximum bandwidth that can be obtained for path P that is in the direction of T. Request for bandwidth reservation along path P so that the video file can be copied using this allocated bandwidth as quickly as possible (606). Check for space availability to store in the incoming video file in the node C (608). If sufficient space is not available, remove the least recently used video file from the store to make room for the incoming file. Copy video data from the current node to C using the reserved path (610). Update cache table at C and S (612). Edge node S maintains the distributed cache across the core nodes so that the availability of a video file in the distributed cache can be easily checked. If C is not the target node T (614), then set the current node as C (616) and perform from step 604 onwards.

[0049]FIG. 7 describes the steps involved in frame streaming. Frame streaming refers to the activity of streaming a requested video file to a client and is done in two phases. In the first phase, that is done before bulk copying, frame streaming is from a non-PoP node to the client. This non-PoP node can either be an edge node or a core node. In the second phase, that is done after bulk copying, frame streaming is from a PoP node that is an edge node close to the client. Let VF be the video fie that needs to be streamed to the client 1 (702). Let C be node with the required video file in cache and T be that target edge node (PoP node) that is close to I. Check whether C is an edge node (704). If C is not an edge node, the path P for frame streaming is from C to I through T via an IP network such as Internet/intranet (706). This is because T is the edge node that is close to I. On the other hand, if C is an edge node, then the path P used for streaming is from C to I via Internet/intranet (708). Locate VF in cache of C (710). Determine the current frame CF (712). CF is I if the streaming is a fresh streaming from the beginning of the video file and is greater than 1 if the streaming is a continuation streaming. Note that the second phase frame streaming is typically a continuation streaming. Establish a connection to support streaming to the client I along the path P (714). Skip data until current frame data is obtained (716). Get next frame (718). If end of VF is not reached (720) and stop signal has not been received (722), send the frame along the established connection (724) and steps 718 through 724 are repeated. Note that the stop signal is received during phase I frame streaming when it is required to switch streaming transparently from one node to another edge node. On the other hand, if end of VF is reached (720) or stop signal has been received (722), then close the connection and VF (726).

[0050]FIG. 8 describes the various factors involved in routing table management. Each node, edge or core, has one or more links and these links interconnect the nodes of the SON (802). The aggregate capacity of the links of a node is the total bandwidth provided by that node. Assuming link aggregation while transporting data across multiple links to a neighboring node, it is adequate to maintain only the link aggregated bandwidth. The Connectivity/Available Bandwidth Matrix (ABW), maintained by each edge node, contains the available bandwidth between a pair nodes that are directly connected via a link. Edge nodes of the SON form a logical ring (804). In order to facilitate efficient transmission of data among edge nodes, the required bandwidth is reserved for interconnection of these edge nodes. The bandwidth contained in the connectivity/ABW matrix doesn't include the reserved bandwidth and is used solely for bulk copying purposes. The available bandwidth is dependent on status of links and nodes, and this status needs to be tracked continuously to maintain an accurate estimate of the available bandwidth. Each node monitors the health of the associated links and communicates any change in BW availability to edge nodes by multicasting (806). Further, each node also monitors the health of its neighbors and communicates any unavailability to edge nodes by multicasting (808). In order to ensure that these health and status messages reach the edge nodes, required bandwidth is kept reserved in each node for this purpose. About FSBW percentage of BW is reserved in each core node for frame streaming and health monitoring/status message communication purposes (810). Only a small portion of a video gets frame streamed from a core node to a client node and most of the video streaming to the client node occurs from a PoP (edge) node. Similarly, a small portion of BW is dedicated in each edge node for receiving health/status messages from core nodes. The load on the SON is directly controlled by the edge nodes of the SON and these edge nodes keep track of the status of each of the core nodes such as available bandwidth and available cache space. Entire traffic through the SON is controlled by these edge nodes (812). Before bulk copying, the selected sub-path BW is updated onto ABW matrix (814). As ABW matrix is maintained at each edge node, it is essential to keep this matrix synchronized across the edge nodes. This is facilitated by using a token manager so that each edge node obtains the token, updates ABW matrix, communicates the changes to other edge nodes, and releases the token. Once the bulk copying is completed, the availability of the selected sub-path is updated onto ABW matrix (816). Again, in order to keep the ABW matrix synchronized, an edge node obtains the token, updates the ABW matrix, and releases the token.

[0051]FIG. 9 describes the steps involved in BW management. BW management involves maintaining an accurate information on the available bandwidth and ensuring that bandwidth doesn't get over-allocated. This is achieved by selecting an edge node arbitrarily as token manager and all the edge nodes communicate with this edge node for obtaining and releasing the token (902). The token manager assures that the token is granted to only one edge node at any point in time, thereby preserving the integrity of the ABW matrix. Each edge node sends a token request to the token manager (904). This token is essential to reserve the bandwidth across a sub-path. On-sub-path selection, before the initiation of bulk copying, send a token request message to the token manager (906). On receipt of the token, check whether the required bandwidth along the selected sub-path is available (908). If available (910), update the ABW matrix and communicate the changes in the ABW matrix to the other edge nodes (912). And, release the token back to the token manager (914). On other hand, if sufficient BW is not available (910), obtain the next best path and BW (916). If available (918), perform from the step 912 onwards.

[0052]FIG. 10 describes the steps involved in token management. An arbitrarily selected edge node acts as a token manager and grants the token to the requesting edge node (1002). Token manager receives two kinds of messages: Token request message and Token release message. On receiving token request message from an edge node E (1004), check the token queue (1006). If the token queue is empty (1008), put E at the head of the token queue (1010). Grant the token to E (1012). On the other hand, if the token queue is not empty (1008), add E to the tail of token queue (1014). Inform E about the token queue status (1016). On receiving token release message from an edge node E (1018), remove E from head of the token queue (1020). Check the token queue (1022). If the token queue is not empty (1024), remove node E1 from head of the token queue (1026) and grant token to E1 (1028).

[0053]FIG. 11 describes the steps involved in determining a route from a source node to a target edge node. The route determination involves identifying a best possible sub-path from a given node towards the target edge node with as much bandwidth as possible. Steps 1104 through 1126 describe the sub-path identification procedure (1102). The best sub-path to be determined is to determine a route from either an edge or a core node to an edge node (1104). Let S be source node and T be the target edge node (1106). Determine a straight line (R) from S to T (1108). Find the nodes (N) such that each node N1 in N is close to the straight line R and the direction of R and the direction of straight line from S to N1 are the same (1110). Remove nodes (X) from N that are not in the path from S to T (1112). Note that the path doesn't contain any cycles. For each node M in N, perform the steps 1116 through 1118 (1114). Determine a sub-path from S to M (1116). Determine the maximum available BW along the sub-path (1118). Arrange the determined sub-paths in the order of closeness to R and on BW (1120). Select a best possible sub-path P (1122). The end node of P is either a core node or the target edge node T (1124).

[0054]FIG. 12 describes the various factors involved in video file cache management. The distributed caching is undertaken to achieve the objective of streaming videos, from the edge nodes of the SON to the client nodes, with a least demand on the network bandwidth. Both edge nodes and core nodes cache the most recent video files (1202). Each edge node maintains the cache distribution across the core nodes due to the bulk copying initiated by this edge node (1204). This cache is called as edge cache. The edge node also stores the core node ID as part of the cache so that whenever a request is received for streaming a video file and it is located in the distributed cache, the edge node instructs the corresponding core node to address the streaming requirement. Each core maintains the cache information related to the most recent videos received by the core node (1206). This cache is called core cache. The core node also stores ID of the edge node that directly or indirectly initiated the bulk copy of the corresponding video data. Edge node, on receiving a video data either from a video server, from a core node, or from an edge node, updates its cache store (1208). During cache updation, if it is observed that the cache is full, the least recently accessed criterion based on last access time is used to find the video data to be removed from the cache to make room for the incoming new video data (1210). Core node, on receiving a video data either from an edge node or from a core node, updates its cache store (1212). During cache updation, if it is observed that the cache is full, the least recently accessed criterion based on last access time is used to find the video data to be removed from the cache to make room for the incoming new video data (1214). The fact that a video data has been removed from the cache is informed to the edge node that either directly or indirectly bulk copied the video data to the core node.

[0055] Thus, a system and method for effectively utilizing server resources by streaming video from the edge nodes of a dedicated streaming overlay network and network infrastructure by using the location based bandwidth allocation and management, and piecewise streaming has been disclosed. Although the present invention has been described particularly with reference to the figures, it will be apparent to one of the ordinary skill in the art that the present invention may appear in any number of systems that maximize the utilization of resources used in video streaming. It is further contemplated that many changes and modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the present invention. ACRONYM LIST 1. ABW Available Bandwidth 2. BW Bandwidth 3. FSBW Frame Stream Bandwidth 4. ON Overlay Network 5. PoP Point of Presence 6. PWVS Piecewise Video Streaming 7. SLA Service Level Agreements 8. SON Streaming Overlay Network 9. VoD Video on Demand 

What is claimed is:
 1. A piecewise video streaming system for maximizing the utilization of server and network resources of a streaming overlay network to meet quality of service requirements under loaded conditions, said piecewise video streaming system comprising: (a) an interactive video client subsystem for managing user interactions and display, said interactive video client subsystem comprising: a server interaction element for requesting a video server for a video; and a client overlay network interaction element for receiving said video stream from a plurality of edge nodes of a streaming overlay network, wherein said streaming overlay network is a part of said piecewise video streaming system; (b) a video on demand service subsystem for managing a video request from a user for a video, said video on demand service subsystem comprising: a client interaction element for receiving said request for said video from said user; a server overlay network interaction element for interacting with an edge node of a streaming overlay network, wherein said streaming overlay network is a part of said piecewise video streaming system; and a video request processing element for processing said request; and (c) a streaming overlay network subsystem for efficient streaming using a streaming overlay network with a plurality of edge nodes and a plurality of core nodes, said streaming overlay network subsystem comprising: a bulk copying element for copying a video file from a node of said streaming overlay network to another node of said streaming overlay network; a frame streaming element for streaming a video from a node of said streaming overlay network to a client; a bulk caching element for caching a video file; a routing and bandwidth management element for maximally utilizing the available bandwidth across said streaming overlay network; and a cache management element for managing a plurality of video files in a cache associated with a node of said streaming overlay network.
 2. The system of claim 1, wherein said client overlay network interaction element of said interactive video client subsystem comprises means for interacting with said streaming overlay network for receiving a video from a source node of said streaming overlay network and from a target edge node of said streaming overlay network, said interaction further comprises: receiving a source input from said source node; determining a frame data and a control data from said source input; buffering said frame data in a buffer; displaying data in said buffer; analyzing said control data for a change in source; receiving a change over frame number from said source node; receiving, buffering, and displaying input from said source node until said change over frame number; and receiving, buffering, and displaying input from said target node from said change over frame number onwards.
 3. The system of claim 1, wherein said video request processing element of said video on demand service subsystem comprises means for processing a request on a video server for a video from a video client, wherein said processing comprises: configuring said video client to receive video streams from a target node of said streaming overlay network; configuring said video server to interact with a source node of said streaming overlay network; receiving of said request for said video by said video server; communication of said request by said video server to said source node; checking of availability of said video in cache; communicating data related to said video to said client when said video is not found in cache by said source node, wherein said communication comprises: receiving said video from said video server by said source node; streaming of said video from said source node to said client; bulk copying of said video to said target node; determination of a change over frame number; streaming from said source node until said change over frame number; and streaming from said target node from said change over frame number onwards; communicating data related to said video to said client when said video is found in cache of said source node by said source node, wherein said communication comprises: streaming of said video from said source node to said client; bulk copying of said video to said target node; determination of a change over frame number; streaming from said source node until said change over frame number; and streaming from said target node from said change over frame number onwards; communicating data related to said video to said client when said video is found in cache of a core node of said streaming overlay network by said source node, wherein said communication comprises: streaming of said video from said core node to said client; bulk copying of said video from said core node to said target node; determination of a change over frame number; streaming from said core node until said change over frame number; and streaming from said target node from said change over frame number onwards; and communicating data related to said video to said client when said video is found in cache of said target node by said source node, wherein said communication comprises: streaming of said video from said target node to said client.
 4. The system of claim 1, wherein said bulk copying element of said streaming overlay network subsystem comprises means for copying a video file from a source node of said streaming overlay network to a target edge node of said streaming overlay network by using a plurality of intermediate core nodes, wherein said copying comprises: obtaining a sequence of piecewise best possible paths initially from said source node to finally reaching said target node, wherein bandwidth of each piecewise best possible path of said sequence is maximal and directional alignment of each of piecewise best possible path of said sequence with a straight line joining said source node and said target node is maximal; obtaining said sequence of piecewise best possible paths a piecewise path at a time; identifying a source piecewise node and a target piecewise node as end points of said piecewise path; reserving bandwidth for said piecewise path; checking for the space availability in a cache of said target piecewise node and removing a least recently used file from said cache if sufficient space is not available; copying said video file from said source piecewise node to said target piecewise node along said piecewise path; identifying a source edge node based on a cache table information associated with said source piecewise node; and updating a cache table at said source edge node and a cache table at said target piecewise node.
 5. The system of claim 1, wherein said frame streaming element of said streaming overlay network subsystem comprises means for launching a video file from a source node of said streaming overlay network to a client, wherein said launching comprises: determining a target edge node of said streaming overlay network that is close to said client; determining an overlay path for frame streaming from said source node to said target edge node; determining said video file in cache of said source node; internal streaming said video file from said source node to said target node using said overlay path; external streaming said video file from said target node to said client node using an IP network; and stopping said internal streaming and said external streaming on receiving stop signal from a node of said streaming overlay network.
 6. The system of claim 5 wherein said frame streaming element further comprises means for launching a video file from an edge node of said streaming overlay network to a client, wherein said launching comprises: determining said video file in cache of said edge node determining a frame number from where to start streaming of said video file to said client, wherein said determination is based on information received from a node of said streaming overlay network; skipping data from said video file until said frame number; streaming video data from said frame number to said client using an IP network; and stopping said streaming on receiving stop signal from a node of said streaming overlay network.
 7. The system of claim 1, wherein said bulk caching element of said streaming overlay network subsystem comprises means for storing a video file received by a node of said streaming overlay network in a store associated with said node, wherein said storing involves making space for said video file in said store and saving said video file.
 8. The system of claim 1, wherein said routing and bandwidth management element of said streaming overlay network subsystem with an available bandwidth matrix comprises means for management of routing table of said streaming overlay network, wherein said management comprises: reserving bandwidth to facilitate communication of among a plurality of edge nodes of said streaming overlay network; reserving bandwidth to facilitate frame streaming from a node of said streaming overlay network; determining a link health of a plurality of links of a node of said streaming overlay network; determining a node health of a node of said streaming overlay network by a neighbor of said node; updating said available bandwidth matrix using available bandwidth computed based on said link health and said node health; updating said available bandwidth matrix with a reserved bandwidth information to facilitate a bulk copying activity; performing the said updation of said reserved bandwidth using a token manager to keep available bandwidth matrix in a plurality of edge nodes of said streaming overlay network in sync with each other; updating said available bandwidth matrix with a released bandwidth information after the completion of said bulk copying activity; and performing the said updation of said released bandwidth using token manager to keep available bandwidth matrix in a plurality of edge nodes of said streaming overlay network in sync with each other.
 9. The system of claim 8 wherein said routing and bandwidth management element further comprises means for bandwidth management of said streaming overlay network, wherein said management comprises: identifying an edge node of said streaming overlay network as a token manager; sending of a token request message to said token manager; receiving of a token grant message from said token manager; determining a required bandwidth along a path; checking the availability of said required bandwidth using said available bandwidth matrix; updating said available bandwidth matrix; communicating said required bandwidth to a plurality of edge nodes of said streaming overlay network; and sending a token release message to said token manager.
 10. The system of claim 8 wherein said routing and bandwidth management element further comprises means for token management using a token queue, wherein said token management comprises: identifying an edge node of said streaming overlay network as a token manager; processing of token request message, wherein said processing comprises: receiving a token request message from an edge node of said streaming overlay network; checking of said token queue; sending token grant message to said edge node if said token queue is empty; and adding said token request message to tail of said token queue; and processing of token release message, wherein said processing comprises: receiving a token release message from an edge node of said streaming overlay network; removing token request message from said edge node from head of said token queue; and removing token request from a waiting edge node from head of said token queue if said token queue is not empty; and send token grant message to said waiting edge node.
 11. The system of claim 8 wherein said routing and bandwidth management element further comprises means for route determination from a source node of said streaming overlay network to a target node of said streaming overlay network, wherein said determination comprises: determination of a target straight line from said source node to said target node; finding a plurality of near nodes of said streaming overlay network, wherein each of said plurality of near nodes is close to said target straight line and direction of said target straight line and a straight line from said source node to each of said plurality of near nodes is same; determining a plurality of select nodes from said plurality of near nodes by removing nodes from said plurality of near nodes that are not in a cycle free path from said source node to said target node; determining a plurality of sub-paths, wherein each of said plurality of sub-paths is a path from said source node to a node in said plurality of select nodes; determining a maximum available bandwidth for each of said plurality of sub-paths; arranging said plurality of sub-paths on said maximum available bandwidth and closeness to said target straight line; and selecting a best sub-path as a route between said source node and said target node based on said arrangement of said plurality of sub-paths.
 12. The system of claim 1, wherein said cache management element of said streaming overlay network subsystem comprises means for managing a plurality of video files stored in a cache of an edge node of said streaming overlay network and in a cache of a core node of said streaming overlay network, wherein said managing comprises: managing an edge cache containing a plurality of video files in said edge node of said streaming overlay network; managing a core cache containing a plurality of video files in said core node of said streaming overlay network; updation of said edge cache on receiving of a video file from a video server, a core node of said streaming overlay network, or an edge node of said streaming overlay network; replacement of a least recently used video file in said edge cache if said edge cache is full; updation of said core cache on receiving of a video file from a core node of said streaming overlay network or an edge node of said streaming overlay network; and replacement of a least recently used video file in said core cache if said core cache is full.
 13. An apparatus for piecewise video streaming for maximizing the utilization of server and network resources to meet quality of service requirements under loaded conditions, said apparatus comprising: a plurality of client computer systems for executing procedures related to interactive video client subsystem comprising: a software subsystem for interacting with a server; and a software subsystem for interacting with a streaming overlay network; a plurality of server computer systems for executing procedures related to video on demand service comprising: a software subsystem for interacting with clients; and a software subsystem for interacting streaming overlay network; a plurality of edge node computer systems for executing procedures related to the efficient streaming using a streaming overlay network comprising: a software subsystem for bulk copying; a software subsystem for frame streaming; a software subsystem for bulk caching; a software subsystem for routing and bandwidth management; and a software subsystem for cache management; and a plurality of core node computer systems for executing procedures related to the efficient streaming using a streaming overlay network comprising: a software subsystem for bulk copying; a software subsystem for frame streaming; a software subsystem for bulk caching; and a software subsystem for routing.
 14. An apparatus, for piecewise video streaming for maximizing the utilization of server and network resources to meet quality of service requirements under loaded conditions, coupled to a communication system, comprising: an IP network for interconnecting a plurality of video clients to a plurality of video servers; a streaming overlay network comprising a plurality of edge nodes connected to a plurality of interconnected to core nodes; a server network for interconnect each of said plurality servers with a node of said plurality of edge nodes; and an edge network for interconnecting each of said plurality of edge nodes with said IP network.
 15. The apparatus of claim 14, wherein said apparatus is further coupled to a communication system comprising: a plurality of said streaming overlay networks; a plurality of overlay networks, wherein each of said plurality of overlay networks consists of a plurality of edge nodes connected to a plurality of interconnected core nodes; and an interconnection of said plurality of streaming overlay networks with said plurality of overlay networks, wherein said interconnection yields a hierarchical network of said plurality of streaming overlay networks and said plurality of overlay networks. 